Prime Directive - Isn't that a Bullywug?
The Klingon Empire is effectively a feudal monarchy, with power residing in the Emperor, who was traditionally a descendant of a Klingon names Kahless. Real power actually lies with the Klingon High Council, rather than the Emperor. The position of emperor was abandoned (but not officially abolished) in the mid-21st century (but is revived much later in 2369 when a group of clerics created a clone of Kahless, who was accepted as the new Emperor) with the leader of the council being the Chancellor.
The High Council consists of twenty-four members representing various Great Houses (tuqmey, essentially, the nobility). The Chancellor is protected at all times by the Yan-Isleth, the Brotherhood of the Sword.
Women were not normally permitted to hold seats on the High Council. However, Azetbur, the daughter of Chancellor Gorkon, was permitted to succeed him as Chancellor in 2293 (as seen in the film Star Trek VI: The Undiscovered Country). It is possible that this was permitted because she was made the head of her house, due to the unusual circumstances of her father's death. Unfortrunately Azetbur was assassinated (see the novel, "Serpents Among the Ruins") by a Klingon named Ditagh, who hoped that after her death the more powerful General Kaarg would rise to power. Kaarg would indeed rise to power and it would be him that would forbid women ever on the High Council again.
Various factions almost constantly challenged the leadership of the Empire, and so over time the Klingons developed a strict and rigorous Rite of Succession to determine their leader. According to tradition, one was permitted to challenge the leader on the grounds of cowardice or dishonorable conduct and fight in single combat. Should the challenger slay the incumbent, he assumed the role of the new leader.
Because of the Klingon propensity for violence, shrewd Klingon chancellors redirected hostilities outward, to avoid Klingon hostility beig turned inwards and cause a civil war. Despite the best efforts of Chancellors there is frequent feuding between the various Great Houses with intrigue and dishonorable subterfuge sometimes mixed up in the more direct and confrontational forms of Klingon politics. Most often, the challenge was made on the floor of the High Council and resolved on the battlefield. However, on occasion, some dishonorable House leaders chose to make more insidious attacks by undermining the standing of their enemies. Klingon politics is often a bloody and vicious affair with many would be leaders and their aides finding they fall to an opponent's Mek'leth.
The main currency unit of the Empire was the darsek although Klingons will trade in most major currencies or trade goods. Their frequent alliances with the Lyrans against the Hydrans and the Kzinti lend them to accept Lyran currency when needed, although they value their own currency more. Their later relations with the Romulans allow their former enemies to regain much of their lost ship-building capabilities after the Gorn-Federation alliance almost left the Romulans without the capability to produce warp-capable ships.
The destruction of the Empire's key energy-production facility on the moon of Praxis was a catastrophic event from which recovery was impossible due to the strain of the Empire's enormous military budget on the resources of their economy. This event was critical in establishing peaceful overtures between the Empire and the Federation. (See the events at the end of Star Trek VI: The Undiscovered Country)